The downpayments received by the company under the provisions of Section 18592, may be held by the company in trust in a separate bank account or depository, or in lieu thereof, the company may maintain a time deposit with a bank, savings and loan association, or comparable institution, or obtain a certificate or certificates of deposit or a clean and irrevocable letter or letters of credit from a bank, in an amount at least equal to the average amount of such downpayments being held at any given time by the company as ascertained by the commissioner, and which are payable to the insurer pursuant to the terms of the premium finance agreement. Such
deposits, certificates, or a clean and irrevocable letter or letters of credit shall be held in trust for the benefit of the insureds, as their relative interests in such downpayments may exist at any given time, and in the event of the insolvency of a company, such funds on deposit under the provisions of this section or as represented by a certificate or certificates of deposit or a clean and irrevocable letter or letters of credit shall be first applied to remitting the amount of the downpayment to the insureds on all premium finance agreements upon which the company has not then forwarded in full the downpayments collected from and then being held for insureds, and, if insufficient to pay all such amounts in full, then such funds shall be applied for such purposes pro rata.